Study Design: Prospective, randomized, controlled. The volunteers will be asked randomly assigned to breathe through the BVGA/Face mask followed by the same protocol with the Face-mask/BVGA: 5 minutes room air, 5 minutes 100% oxygen, and 5 minutes room air again. The BVGAs/face masks well be connected to a standard operating room ventilation machines, and cardiopulmonary parameters will be monitored and documented.